This invention relates generally to a reciprocating internal combustion engine, and more particularly, to apparatus and a method for detecting and determining the severity of faults in individual cylinders of the engine using temperature data representative of true exhaust temperatures from the respective cylinders.
It is well known that the diagnosis or detection of faults in cylinders of internal combustion engines can be a tedious time-consuming process resulting in extended downtime, reduced productivity and increased operational costs. Undiagnosed or undetected cylinder faults can also shorten the lifespan of an engine and necessitate expensive repairs. Reference in this regard, R. K. Autar, Automated Diagnostic Expert System For Diesel Engines, Heavy Duty Engines, A Look At The Future, American Society of Mechanical Engineers, Internal Combustion Division (publication) I.C.E. 2294, which discloses an automated diagnostic system based on artificial intelligence criterion using mechanical signature analyses of signals acquired from engine mounted sensors. The system uses vibration signals together with oil pressure and temperature, crankcase pressures, exhaust gas temperature and pressure, exhaust emissions, manifold noise levels, inlet manifold pressure, fuel delivery pressure, and instantaneous engine speed. Reference also Paul J. O""Sullivan, Advance Engine Diagnostics Using Universal Process Modeling, Maintenance Technologies SAE. Special Publications volume 1188 1986, SAE, Warrendale, Pa. U.S.A., which discloses an engine diagnostic tool for avoiding component failure using a universal process modeling technique wherein early warning signals are detected by monitoring a number of system parameters, such as exhaust temperature, engine vibration and inlet manifold pressure, and generating computer models to simulate the operation of the engine using a library of past information as reference data. However, a shortcoming of systems and tools such as these is the need for sensor data collection from a relatively large number of sensors.
Referenced further, Schricker U.S. Pat. No. 5,566,091 issued Oct. 15, 1996 to Caterpillar, Inc. which discloses a method and apparatus for machine health inference by comparing two like loaded components, wherein operating parameters of the components are sensed, differences therebetween are determined, averaged, and then trended for determining relative performance of the components. Determining machine health using trend data according to this method is effective for constant speed or near steady load applications. However, such method is less advantageous when a machine operates under dynamic work cycle conditions during which exhaust gas temperature can vary by hundreds of degrees over a relatively short time period. In particular, under dynamic conditions, using the known trending methods it is difficult to determine small temperature deviations, of, for instance, about 20xc2x0 or so, which have been found to be an indication or a clue to the existence of cylinder faults such as intake or exhaust valve problems such as guttering, a weak or leaking fuel injector, and the like. Here, xe2x80x9cgutteringxe2x80x9d is generally defined as a channeling of the face of the valve as a result of corrosion or the like, and is a problem as it can give rise to gas leakage past the valve and potential breakage of the valve head. It is also difficult to determine the severity of various cylinder faults and problems using the known systems and methods.
Accordingly, the present invention is directed to overcoming one or more of the problems as set forth above.
In one aspect of the present invention, a method for detecting and determining severity of a fault in a cylinder of an internal combustion engine useful under both steady-state and dynamic operating conditions is disclosed. The method includes the steps of:
(a) collecting temperature data representative of temperatures of exhaust from the cylinder;
(b) estimating true temperatures of the exhaust as a function of the collected temperature data;
(c) determining deviations of the estimated true temperatures from at least one reference value; and
(d) determining at least one severity symptom value for the cylinder as a function of the deviations determined, and comparing the at least one severity symptom value with at least one predetermined reference value for a known cylinder condition.
In another aspect of the present invention apparatus including elements for detecting and determining severity of a fault in a cylinder of an internal combustion engine under both steady-state and dynamic operating conditions is disclosed. The apparatus includes an element for estimating true temperatures of exhaust from the cylinder as a function of collected temperature data and at least one compensation factor, an element for determining deviations of the estimated true temperatures from at least one reference value, and an element for determining at least one severity symptom value as a function of the deviations determined, and comparing the at least one severity symptom value with at least one predetermined reference value for a known cylinder condition.